Population Growth Across U.S. Census Divisions

Over the last 10 years, the Mountain division has shown the highest compound average annual population growth, at a rate of 2.2%, followed by the South Atlantic, at 1.6%. The Mid-Atlantic was the lowest, at 0.4%. According to the most recent population estimates, the South Atlantic is the most populous Census division, with a total population of about 56.8 million; New England is the least populated, with14.3 million people.

There is an trend taking place in the country, with population shifted toward the South and West. The Mountain states—including Nevada, Arizona, and New Mexico—have experienced particularly rapid population gains in recent years. On the other hand, population growth in some of the most populous Census divisions—such as the East North Central and the Mid-Atlantic—was less than 1.0% over the same period

The single most important factor in determining population growth is the total fertility rate (TFR). This rate—the estimated average number of births per woman in a lifetime, based on the age-specific birth rates observed in a given year—varies by state, ranging from 1.7 in Vermont to 2.6 in Utah. Rates tend to be lower in Northeastern states and higher in Southwestern states, mostly due to the latter's larger populations of immigrant groups with higher birth rates.

Net migration is the other highly significant factor in determining population growth. The South Atlantic division, which ranked second in total population growth during 1996–2006, also had the highest positive net migration in absolute terms during the first quarter. But the Mountain region, which includes Nevada and Arizona, is fast catching up with this trend.

One of the most significant factors contributing to positive net migration is rapid employment growth, which leads to a demand for more workers that cannot be fully met by the local labor force. In the first quarter of 2006, for example, the Mountain division had employment growth of 4.1% year-on-year (y/y), the highest in the country. Similarly, the South Atlantic division had job growth of 2.5 % y/y last quarter, which has helped to attract population. As commonly noted, people follow jobs, and this has a multiplier effect on the state economy. The increased spending due to new residents, in turn, fuels economic activity, leading to the creation of even more jobs and boosting overall economic prosperity. Nevada and Arizona are the current shining examples of this "virtuous" cycle.